The type of wood that sinks in water will depend on its density. Generally, hardwoods such as oak, mahogany, teak, and walnut are denser than softwoods such as pine, cedar, and spruce. Therefore, hardwoods are more likely to sink in water than softwoods.
However, even within a particular species, the density can vary based on the growth conditions and the age of the tree. So, it is not always easy to predict whether a particular piece of wood will float or sink in water based solely on the type of wood it is made from.
In summary, if you want to find wood that will sink in water, you should look for hardwoods that have a high density.